Bradford & Bingley said Christopher Rodrigues, who has led the bank for the last eight years, is leaving to become the president and chief executive of US-based Visa International.

The boss of the former building society's core lending and savings business, Steven Crawshaw, will replace Mr Rodrigues at the end of this month.

Under the leadership of Mr Rodrigues, Bradford & Bingley has pursued an aggressive expansion strategy since joining the London Stock Exchange in 2000.

The group has transformed itself from a traditional mortgage and savings specialist to offering a diverse range of financial services by buying a string of mortgage books and financial advice businesses.

It has been building up its mortgage business by focusing on niche lending, rather than the low margin "plain vanilla" or first-time buyers market.

Last month, the bank said annual profits in its specialist lending arm Mortgage Express, which specialises in niche markets such as buy-to-let, climbed 9% to £263m.

Balances in the unit surged to £13.6bn, passing its old building society book for the first time and fuelling hopes that it will drive profit growth this year.

B&B's chairman Rod Kent thanked Mr Rodrigues for his "strong leadership" during his time at the helm, which included the flotation.

"I wish Christopher every success in his new job," he said.

Mr Crawshaw, 42, will take over from Mr Rodrigues on March 31.

Under his leadership, the group's lending and savings business has seen substantial growth in the last three years.

Mr Crawshaw joined B&B in 1999 as its flotation programme director and was appointed to the group's board in January 2002.

As head of the flotation programme, he managed the demutualisation of the former building society into Bradford & Bingley PLC.

He has also had spells as the group's director of strategy, human resources, IT and other areas.

He previously worked for former building society Cheltenham & Gloucester and banking group Lloyds TSB.

Mr Crawshaw said he was confident about the group's strategy and was clear about its priorities "in both the short and medium term".